[BUGFIX] Fix undefined array key in DatabaseRecordList

When transferring a item to the clipboard on the root
page (uid=0), an undefined array key warning is thrown.

This is fixed by properly checking the array key.

Resolves: #94771
Releases: master
Change-Id: I2280468ee37b3fdeb264a384e6ec82f855a5476e
Reviewed-on: https://review.typo3.org/c/Packages/TYPO3.CMS/+/70392


Tested-by: Oliver Bartsch <bo@cedev.de>
Tested-by: core-ci <typo3@b13.com>
Tested-by: Benni Mack <benni@typo3.org>
Reviewed-by: Oliver Bartsch <bo@cedev.de>
Reviewed-by: Benni Mack <benni@typo3.org>